Improvement in speaking-telephones



E. GRAY. Spe@Lking-Telephone.

No. 207,269. Patented Aug. 20,1878.

UNITED STATES PATENT OEETcE.

- 1 ELIsnii GRAY, or el'iidxco, itmxois.

`IMPROVEMENT iN SPEAKINGfTELEPHONS.

Specitcation forming pnrt of Letters `Patent N 207,2G9,'dated August 30,l-n; appliraticn tiled J une 20, 1678.` Y

To all 'whom it may concern:

Be it known that I, ELIsHA GRAY, of Chicago, in the county of Cook andState -of Illinois, have invented certain new and useful Improvements inApparatus for Generating, '.liansxnitting, and Reproducin g RhytlnnicalVibrations, representing spoken words or vocal sounds, in an electriccircuit, of which improvements the following is a specification:

My present invention more especially relates to and constitutes animprovement upon my bipolar telephone, for which Letters lat ent of theUnited States No. 204,029 were granted to me May 21, 1878, which patentshowstwo telephones so combined witlra bifurcated mouth-piece that eachis actuated with equal force,'thereby greatly increasing theelectro-motive force which generates the rhythmical vibrationsVrepresenting the vocal sounds or words articulated or spoken into thetelephone.

The object of my present invention is still further to increase the4electro-motive force or rhythmical genera-ting capacity of t-hetelcphone, and to secure an increased volume and clearness of sound,while preserving the portable features ot the instrument, so as toenable it to be handled with facility; to which ends my improvementconsists in certain novel combinations, constructions, and organizationsof parts, hereinafter specifically claimed.

The aecompanyin g drawings represent so much ot my improved instrumentas is necessary to illustrate the subject-matter herein claimed, asconstructed in the best way now known to lne. Obviously, however, someofthe improvements may be used without the others, and in apparatusdiffering somewhat in its details of construction from those of thatherein shown, without departing from thc spirit of my invention.

Figure 1 represents a plan or top view of a bipolar telephone with itsdiaphragms and electro-magnets duplicated, and arranged in reverse orderon each side'of each ofthe poles of its permanent magnet. Fig. 2represents a side elevation, partly in section therethrough, on the line2 2 of Fig. 1, showing the details of the method of constructing andconnecting eachA pair of the diaphragms.` Fig. 3 represents thearrangement upon circuit of my im; proved apparatus.

The details of construction ot the present apparatus are substantiallythe same as those of my bipolar telephone hereinbefore meltv Thesoft-iron core D is made tubularand extends through the pole of thepermanent magnet 011 each` side, so as' to receive Aa supplementaryhelix or wire coil, C', in addition to the usual one on the oppositeside of the pole.

A secondary diaphragm, E', is mounted in front of the supplementaryelectro-magnet in precisely the same manner as its correspondingdiaphragm, E. The arrangement of the seconda-ry magnet and its diaphragmrelative- .ly to the pole is, however, it wiil be observed, i,

reversed, so as to bring the electro-magnets next the pole and betweenthe diaphragms. The secondary cap F, which protects the diaphragm E', ismade solidf-that is, it has no opening for a month-piece, suchconstruction being unnecessary in this instance.

The core D has a small hole drilled through it from end to end, aboutone-eighth of an inch in diameter. A light rod', d', of wood or someAnon-magnetic meta-l, (sue-h as brass, for in.,-

stance,) passes through this opening,iuwl1ich it is capable ot movingfreely endwise..i Each end or" this rod is attached to its respectivediaphragm E t", so that the movement of one from any cause whateverproduces corresponding movements or vibrations in the other'.

rlhe obvious advantage of my improvement is, that I am enabled, underthe organization of i part-s above described, to vibrate two diaphra gmsin front of two electro-n1agnets, both of which `are charged from thesame pole of the permanentmagne ,withoutmaking any change in'any respectin the bifuroated mouth-piece shown in my bipolar patent, abovementioned. I have demonstrated by experience that by this method I cangenerate much greater electro-motive force than could be done by theemployment of a single diaphragm, and am,-

consequently, enabled to produce amuch louder and clearersound.

A similar apparatus is attached to the other pole of the permanentmagnet, and I am thus enabled to vibratefour diaphragms instead of two,as in my bipolar telephone, above mentioned, and still retain the samerelation between the diaphragms and mouth-piece, as in the aforesaidinstrument. v

The arrangement upon circuit which I deem most advantageous is one whichkeeps all the magnets permanently charged, which -is preferably' done(where. a permanent magnet is not used) by 'working with what is knownas a closed circuit, such as that shown in Letters Patent of the UnitedStatesNo. 186,340, granted to/me January 16, 1877, or inA twoapplications forLetters Patent respectively led by me October 29, 187 7,1,) and January 17, 1878. e

The operation ofthe apparatus. will readily of the United States, (Oasebe understood from )the foregoing description.

A I do not broadly, claim hereinA vibrating a secondary diaphragm fromaprimary one, nor the combination of a magnet, two diaphragms,

and an interposed air-tight chamber, as these subjects-matter areembodied 'in another application iled by me May 8, 1878, of'which'thisis a division, but limit the claims to' the combinations specified.

poles, a wire coil or pole, and a diaphragm for each helix;

I claim as my invention-- t V 1. A secondary magnet, in combination witha secondary diaphragm, actuated by a primary diaphragm through theintervention of a conmeeting-rod, substantially as hereinbefores'etforth, toincrease the electro-motive force of the vibrations. l

2. In combination, diaphragme mounted. thereon,

a permanentV magnet,

and electromagnets interposed between the diaphragms,-

so that the diaphragme are actuated by'two magnets of similar polarity.l y

i 3. In combination, a permanent magnet,.a tubular soft-iron coremounted *on each of its helix on each side of each 4; Thecombination,substantially as hereinbefore set forth, of a mouth-piece, aprimary diaphragm, a -secondary diaphragm actuated thereby, and a soldcap or cover inclos'ing the Ems-'HA GRAY.

f Witnesses:

l A. G. Swmrwour, D. M. ER'SKINE, Jr.

